


Oblivious Mates

by fangirlingtodeath513



Series: Dean and Cas Bingo [3]
Category: Supernatural
Genre: A/B/O, Consensual Somnophilia, Cuddling & Snuggling, Friends With Benefits, Fuckbuddies, Heat Sex, Knotting, Lack of Communication, M/M, Mating Bites, Mating Cycles/In Heat, Misunderstandings, Naked Cuddling, Rut Sex, Scenting, Spooning, True Mates
Language: English
Status: Completed
Published: 2019-09-01
Updated: 2019-09-01
Packaged: 2020-09-29 07:27:58
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,984
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20431691
Author URL: https://archiveofourown.org/users/fangirlingtodeath513/pseuds/fangirlingtodeath513
Summary: Dean and Cas have been heat/rut fuck buddies for a while now, but Dean's starting to get second thoughts. His feelings evolved a long time ago but now he's feeling guilty about holding Castiel back from finding his true mate.





	Oblivious Mates

**Author's Note:**

> Hey guys! So a quick warning, there's an instance in here where it may seem like nonconsensual somnophilia, but it's definitely consensual. I didn't explicitly write it in there, but it's fully consensual during their heat/rut sessions :)
> 
> Thank you to the lovely [Gii](https://archiveofourown.org/users/heylittleangel) for beta reading this for me! <3
> 
> This is another bingo fill, this time for the 'friends with benefits' square. You can find the masterpost for this bingo right [here](https://fangirlingtodeath513.tumblr.com/post/187103213249/fangirlingtodeath513s-dean-and-cas-bingo).

“Fuck, alpha, knot me, _ please _,” Dean pants, grinding back onto Castiel’s impressive knot. Every cell in his body is screaming for an alpha’s knot and Dean can feel his heat starting to spike again. “Alpha, please,” Dean whines, fingers gripping the sheets tightly. 

Castiel growls, sinking his teeth into Dean’s shoulder as his knot finally sinks past Dean’s rim and locks them together. Cas is careful not to break the skin with his bite, even though Dean really wishes he would. Not that he’d ever say it out loud. He and Cas are best friends and heat/rut fuckbuddies, nothing more.

After a moment, Cas relaxes his jaw and shuffles them around to get comfortable, grunting when the movement tugs on his knot. They end up spooning with one of Cas’s arms slung over Dean’s waist.

Dean can feel the wave of his heat abating, thank gods. He hates being in heat, it’s the worst part of every month. He loves Cas’s rut, loves being pounded into the mattress, _ loves _ letting Castiel loosen up and take what he wants. It makes Dean’s omega purr. But his heat? Awful. He _ hates _ that he’ll do just about anything to get Castiel’s cock while in heat. It’s embarrassing, frankly. The only thing that makes it slightly better is that Castiel seems to enjoy himself during Dean’s heats.

“You okay?” Cas murmurs against the back of Dean’s neck, one of his legs slotted between Dean’s.

“Yeah, man. I’m good. You? Are you comfortable enough? We can move.”

Castiel hums, snuggling closer and pressing a light kiss to the back of Dean’s neck. “Nope. ‘M good here.”

Dean smiles softly, resting his arm over Castiel’s. “Thank you.”

Castiel groans. “Dean, you don’t have to thank me every time you get your heat. This is a mutual thing and I’m _ more _ than happy to do it.”

Dean flushes, grateful that Castiel can’t see his face in this position. “Yeah, but I know it can get annoying.”

“Annoying?”

Dean nods, rubbing the back of Cas’s hand with his thumb. “Yeah, it spikes way more often than your rut does.”

Dean can almost _ hear _ Cas’s eyes roll. “Dean, do you honestly think I don’t enjoy this?”

Dean shrugs.

“I assure you, if I didn’t enjoy spending your heat with you, I would’ve stopped our arrangement a long time ago.”

The thought of Castiel ending their arrangement sends a jolt of pain through Dean, though he refuses to acknowledge it. He knows that their arrangement will eventually end, once Castiel finds his own omega to mate, and then Dean will be forced to watch the love of his life love someone else.

Eventually, Cas’s knot deflates and he slips out of bed. Dean expects him to return to his own room, but instead, he wipes Dean down with a cool washcloth before climbing back into bed and pulling the blankets over them.

“You’re staying?”

Castiel hums, snuggling against Dean’s back again. “If that’s okay, yes.”

“You never stay the night,” Dean says dumbly, half confused and half surprised.

“Is it okay if I do? I can go—”

“No! No, it’s fine. I’m just surprised.”

Castiel yawns. “Your bed is comfortable, and your heat will spike again in a few hours. Easier to just stay here.”

Dean nods, closing his eyes and allowing himself to relax back against Castiel. “Night, Cas.”

He can feel Cas’s smile on the back of his neck. “Goodnight, Dean.”

The next time Dean wakes, it’s to a spike of heat thrumming through his body and Castiel’s thick cock rutting against his ass. Something’s off, though. Castiel’s like a furnace at his back, and he’s gripping Dean’s hip so tightly that Dean’s positive there’ll be bruises there later.

“Cas? Are you okay?”

Castiel whines, teeth scraping the back of Dean’s neck. “My rut’s early. Please, Dean, need you…”

Dean frowns as he grinds back against Cas’s cock. He’s never triggered Cas’s rut before and in all of their nearly seven years of living together, their cycles have never aligned. 

As much as he’d like to dwell on that, he doesn’t have time. Castiel’s rough during his rut and Dean’s heat is prickling underneath his skin. He grunts softly and rolls onto his stomach, throwing what he hopes is an enticing look toward Castiel as he presents for the alpha.

Castiel’s on him in a second, growling as he guides his cock into Dean’s slick-soaked hole. Dean gasps and grabs onto the sheets, gripping them tightly as Cas pounds into him.

Dean hardly has a moment to breathe after that. Castiel’s _ rough _ during his rut, but Dean loves it. He loves waking up with crescent-shaped indents on his hips and Cas’s cum leaking out of his hole. It makes him feel like he’s really Castiel’s, even though he never will be. He’s even fantasized about pups, but he’ll never be Castiel’s omega, so it doesn’t matter.

He lets out a breathless moan as Cas’s knot pops and locks them together and Cas’s mouth settles over Dean’s scent gland. He’d swear he felt the scrape of teeth against his skin before Cas pulled away abruptly, pulling on his knot and forcing a moan from both of them.

“You didn’t come,” Cas says, and Dean can hear the frown in his voice. “Did I hurt you?”

Dean chuckles softly, shaking his head. “Nah, man, just caught up in my own head. I’m good.”

Castiel hums, gently shuffling them around so they’re spooning again. “My rut’s nearly two weeks early,” Cas murmurs, hand resting low on Dean’s stomach.

  
“Mmm,” Dean hums, eyes fluttering closed. “You okay? Should you go to the doctor?”

Castiel shakes his head, yawning. “‘S been getting earlier and earlier for the last few months. Syncing up with you,” he murmurs, nuzzling the back of Dean’s neck.

The admission sends a chill through Dean. Cas’s rut has been syncing up with Dean’s heat? Has his heat been moving as well? He hears Castiel’s quiet snores behind him, so he pushes the thought away and lets himself sleep.

He wakes up to Castiel rocking into him, knot already catching on Dean’s rim.

“Fuck, _ Dean _,” Cas groans, nuzzling against his scent gland. Dean bares his neck, grinding back on Castiel’s cock.

“C’mon, alpha, give me your knot.”

Castiel grunts softly, tightening his arm around Dean’s middle. “Fuck, omega, gonna fill you up so good, breed you full of pups…”

Dean freezes. Castiel’s always been fond of dirty talk while in rut, but he’s _ never _ mentioned pups before.

Castiel’s knot pops and he sinks his teeth into Dean’s shoulder, biting hard enough to break the skin. Dean gasps, a shiver of arousal coursing through him. Castiel growls lowly, jacking Dean off as he laps at the bite.

“My apologies, Dean, I didn’t mean to break the skin.”

Dean waves a hand, snuggling back against Castiel. “I don’t mind. Like you being rough during your rut.”

Castiel smiles against the back of Dean’s neck, humming softly. “Seems like your heat’s nearly over.”

Dean nods, yawning. “Should be, yeah. Today’s the last day.”

They fall silent for a while, at least until Cas nudges Dean’s leg with his own.

“What’s wrong? You smell upset,” Cas murmurs, arm tightening around Dean.

“Why haven’t you ever brought an omega home?”

Castiel doesn’t answer and Dean thinks he may have fallen asleep. His knot deflates and he pulls away, tugging at Dean until Dean rolls over to look at him. “Why would I bring an omega home?”

Dean blinks at Castiel in confusion. “How… how are you going to find your true mate if you don’t look?”

Castiel stares at him for what feels like forever before dissolving into laughter. Dean furrows his brows as he watches his best friend, who’s nearly crying from how hard he’s laughing.

When he doesn’t stop after a while, Dean’s frown deepens and he smacks him with a pillow. “What’s so funny?”

Castiel giggles softly, wiping his face. “That explains a lot. I’d always wondered why you wouldn’t let me bite you.”

Dean stares blankly at him. “You… what?”

“Just do me a favor. You’ve scented me before. What do you smell?”

Dean frowns, so Cas tilts his head and beckons him forward. Still frowning, Dean closes his eyes and inhales Cas’s scent deeply. “Lavender. Honey. Cinnamon.”

Castiel hums. “Have you always smelled cinnamon on me?”

Dean tries to think back, but he can’t ever remember scenting Cas and _ not _ smelling cinnamon. “Yes? Is this a trick question?”

Smiling, Cas shakes his head. “Not really. Cinnamon is _ your _ scent, not mine.”

Dean frowns. “Well, what do you smell on me?”

“Cinnamon, leather, and honey.”

Blinking in confusion, Dean shuffles and tucks his legs underneath himself as he sits up. “You’re saying we’ve been true mates this entire time? We’ve never triggered each other’s cycles before now.”

“I switched birth controls. It’s not as potent, which is why my cycle is moving to match yours.”

“We’re… Cas, why didn’t you say anything?”

Castiel laughs. “I assumed you knew. I thought you just didn’t want me that way.”

Dean scoffs. “I’ve been in love with you for six years!”

“Well, you didn’t tell _ me _ that, how was I supposed to know?”

Dean stares at him for a second before shaking his head and grinning. “We’re a couple of idiots, aren’t we?”

“Indeed we are,” Cas answers, smiling as he pulls Dean into a kiss. 

Dean pouts as the telltale itch of his heat starts under his skin. “Bite me, alpha?”

Castiel frowns. “After my rut ends. I don’t want either of us to be impaired. Besides, we should probably discuss—”

“Cas, there’s nothing to discuss. I’ve been in love with you for six years, that ain’t gonna change. I won’t fight you on the not impaired thing though.”

Cas’s eyes flash red and Dean can smell his rut spiking. Dean smirks, rolling onto his stomach and presenting for his alpha.

Dean’s brain skips as he thinks _ his alpha _ , but then warmth spreads through him and he grins. _ His _ alpha. He likes the sound of that. “C’mon, alpha, knot me.”

Cas’s hands settle on Dean’s hips, but then he’s urging Dean onto his back, much to Dean’s confusion.

“I want to be able to see you,” Cas explains, smiling shyly. Dean smiles back, wrapping his legs around the alpha’s waist and tugging him down for a kiss.

“Want you to knot me, alpha, please? Breed me full of your pups, Cas, c’mon.”

Cas growls lowly when the smell of slick reaches his nose, pushing into Dean in one slow, smooth thrust. “Can’t wait to bite you, little omega, can’t wait until you’re swollen with my pups. _ Fuck _, Dean.”

Dean shivers, tangling a hand in Cas’s hair and dragging him down into a rough kiss. He can already feel Cas’s knot starting to swell and catch on his rim, so he tightens his legs around Cas’s waist, urging him on with soft pleas and dirty talk.

After only a few more thrusts, Cas’s knot locks them together and the alpha wraps a hand around Dean’s cock, jacking him off almost effortlessly. It shouldn’t surprise Dean at this point, they’ve had this arrangement for over six years. Cas knows each and every button to push to get Dean writhing.

Cas grunts softly, frowning. “I shouldn’t have knotted you like this. Why did you let me tie us like this?”

Dean snorts. “Cause you said you wanted to see me and I’m a sap. Just lay down and I’ll sit on your lap ‘til your knot goes down.

Cas hums, wrapping an arm around Dean’s waist and shuffling them around until Dean’s sitting on Cas’s lap. Dean hums happily, leaning down to kiss Cas slowly.

Four days later, they show up at Charlie and Jo’s apartment for game night with fresh mating bites and delighted grins on their faces. 

**Author's Note:**

> Find **this fic** on [Tumblr](https://fangirlingtodeath513.tumblr.com/post/187426381519/oblivious-mates-a-destiel-fanfic-written-for-the) and [Pillowfort](https://www.pillowfort.social/posts/815565)  
  
Find **me** on [Tumblr](https://fangirlingtodeath513.tumblr.com/) and [Pillowfort](https://www.pillowfort.io/fangirlingtodeath513)  
  
**Please don’t post my works anywhere without my permission.**


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